javascript recursive through an object

Question

I want to step recursively through an object for debugging and logging reasons. But my actual code snippet breaks after the first object.

function showData(obj)
{
    for(var key in eval(obj))
    {
        debugWriteLine('object = '+obj+' | property = '+key+' | type = '+typeof(eval(obj+'.'+key))+' | value = '+eval(obj+'.'+key));                    

        if(typeof(eval(obj+'.'+key))=== 'object')
        {
            obj= obj+'.'+key;           
            return showData(obj);
        }
    }
}

showData('$');

This showed me only the content of $ and $.fn but I need all the properties of $.

Thank you Florian

Answer 1

First: You neither need nor want eval for any of this. Start with $ (the object) and then use obj[key] when you are looking into one of its properties. Recurse when that property is a non-function object.

The reason you're not seeing all of the properties is that for-in loops only loop through enumerable properties, and many of jQuery's properties are not enumerable. You can use getOwnPropertyNames to get the names of all string-keyed properties of an object, even non-enumerable ones. And you can use getPrototypeOf to get that object's prototype so you can enumerate its properties (which for-in does).

So:

function showData(name, obj)
{
    while (obj && obj != Object.prototype)
    {
        // Get all of the object's property names, even non-enumerable ones
        var keys = Object.getOwnPropertyNames(obj);
        keys.forEach(function(key)
        {
            // We should restrict this check to function objects; left
            // as an exercise for the reader...
            if (key !== "caller" &&
                key !== "callee" &&
                key !== "arguments"
                )
            {
                var value = obj[key];
                var type = typeof value;
                debugWriteLine('object = ' + name + ' | property = ' + key + ' | type = ' + type + ' | value = ' + value); 

                if (type === 'object')
                {
                    return showData(name + "." + key, value);
                }
            }
        });

        // Get the object's prototype
        obj = Object.getPrototypeOf(obj);
    }
}

Live Example:

var debugWriteLine = console.log.bind(console);
function showData(name, obj)
{
    while (obj && obj != Object.prototype)
    {
        // Get all of the object's property names, even non-enumerable ones
        var keys = Object.getOwnPropertyNames(obj);
        keys.forEach(function(key)
        {
            // We should restrict this check to function objects; left
            // as an exercise for the reader...
            if (key !== "caller" &&
                key !== "callee" &&
                key !== "arguments"
                )
            {
                var value = obj[key];
                var type = typeof value;
                debugWriteLine('object = ' + name + ' | property = ' + key + ' | type = ' + type + ' | value = ' + value); 

                if (type === 'object')
                {
                    return showData(name + "." + key, value);
                }
            }
        });

        // Get the object's prototype
        obj = Object.getPrototypeOf(obj);
    }
}

showData('$', $);

.as-console-wrapper {
  max-height: 100% !important;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>